title: The apoptotic and proliferation rate of tumour budding cells in colorectal cancer outlines a heterogeneous population of cells with various impacts on clinical outcome.
abstract: OBJECTIVE
  In colorectal cancer (CRC), tumour buds represent an aggressive cell type at the invasive front with apparently low proliferation. The aim of this study was to determine proliferation and apoptotic rates of buds in comparison to tumour centre, front and mucosa.
  
  
  RESULTS
  Whole tissue sections from 188 CRC patients underwent immunohistochemistry for Ki67. Ten high-power fields (HPFs) were evaluated in mucosa, tumour centre, tumour front and tumour buds (total = 40 HPFs/case). Caspase-3 and M30 immunohistochemistry were performed on a multipunch tissue microarray from the same cohort. Ki67, caspase-3 and M30 immunoreactivity were correlated with outcome. The average percentage of cells showing Ki67 positivity was 5.2% in mucosa, and was not significantly different between the centre and front of the tumour (38.2% and 34.9%; P < 0.0001); 0.3% of buds showed Ki67 positivity (P < 0.0001). Caspase-3 expression was similar in mucosa, tumour centre and tumour front, but lower in tumour buds (<0.1%; P < 0.0001). M30 staining in buds was decreased (0.01%; P < 0.0001) in comparison to other areas. Ki67 positivity in buds was detrimental to survival in univariate (P = 0.0352) and multivariate (P = 0.0355) analysis. Caspase-3-positive tumours showed better outcome than negative tumours (P = 0.0262); but tumours with caspase-3-positive buds showed a worse outcome than those with caspase-3-negative buds (P = 0.0235).
  
  
  CONCLUSIONS
  Ki67, caspase-3 and M30 staining is absent in most tumour buds, suggesting decreased proliferation and apoptosis. However, the fact that Ki67 and caspase-3 immunoreactivity was associated with unfavourable prognosis points to a heterogeneous population of tumour buds.
authors.affiliation: Clinical Pathology Division, Institute of Pathology, University of Bern, Bern, Switzerland; Translational Research Unit, Institute of Pathology, University of Bern, Bern, Switzerland.
authors.forename: Heather
authors.initials: H
authors.lastname: Dawson
authors.forename: Viktor H
authors.initials: VH
authors.lastname: Koelzer
authors.forename: Eva
authors.initials: E
authors.lastname: Karamitopoulou
authors.forename: Mary
authors.initials: M
authors.lastname: Economou
authors.forename: Caroline
authors.initials: C
authors.lastname: Hammer
authors.forename: Dominique-Elisabeth
authors.initials: DE
authors.lastname: Muller
authors.forename: Alessandro
authors.initials: A
authors.lastname: Lugli
authors.forename: Inti
authors.initials: I
authors.lastname: Zlobec
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D017209:Apoptosis; D014408:Biomarkers, Tumor / Q000235:genetics / Q000378:metabolism; D053148:Caspase 3 / Q000378:metabolism; D049109:Cell Proliferation; D015179:Colorectal Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D053538:Keratin-18 / Q000378:metabolism; D019394:Ki-67 Antigen / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D009361:Neoplasm Invasiveness / Q000473:pathology; D010446:Peptide Fragments / Q000378:metabolism; D011379:Prognosis; D011518:Proto-Oncogene Proteins / Q000235:genetics; D016283:Proto-Oncogene Proteins p21(ras); D012189:Retrospective Studies; D018631:ras Proteins / Q000235:genetics
chemical_list: D014408:Biomarkers, Tumor; C117307:KRAS protein, human; D053538:Keratin-18; D019394:Ki-67 Antigen; C561463:M30 cytokeratin-18 peptide, human; D010446:Peptide Fragments; D011518:Proto-Oncogene Proteins; C505407:CASP3 protein, human; D053148:Caspase 3; D016283:Proto-Oncogene Proteins p21(ras); D018631:ras Proteins
keywords: anoikis; apoptosis; colorectal cancer; proliferation; tumour budding